This application if for a one-year non-renewable grant from the National Eye Institute for pilot studies examining neuropeptides in the normal and diabetic retina. Neuropeptides have been shown to be neurotransmitters in the mammalian brain, and may function as transmitters in the retina as well. However, few studies have demonstrated the presence, much less a role, for the neuropeptides. The studies proposed in this application are designed to expand the information on the peptides somatostatin, substance P, and neurotensin in rat retina. Basic observations on possible changes in the level of these neurotensin in rat retina. Basic observations on possible changes in the level of these neuropeptides in retinas obtained from diabetic animals will also be studied. The proposed studies offer the advantage of separating the peptides by high-performance liquid chromatography prior to radioimmunoassay measurements. This methodology separates the authentic peptide from potentially cross-reacting peptides or peptide-fragments before radioimmunoassay is performed. Thereby, if detected in the radioimmunoassay, the likelihood is increased that these peptides are present in the retina. If these peptides are shown to be present in the retina, and the levels found to be abnormal in diabetic animals, these data may ultimately be of relevance in understanding visual disorders in diabetes.